The present invention relates to a confocal microscope and in particular a confocal microscope which enables real-time imaging to be performed.
In approximately the past fifteen years confocal microscopes have been developed and have been shown to provide advantages over alternative microscopy systems such as greater spatial resolution and depth discrimination. A schematic diagram of a known reflection confocal scanning microscope such as that described in Confocal Microscopyby Tony Wilson, Academic Press (1990) is shown in FIG. 1. The microscope consists of a laser light source 1 from which laser light passes to a lens 2 for generating a diffraction limited spot of light. The spot of light is reflected from an object 3 which is being scanned and the reflected light is extracted by a half silvered mirror 4 and then passed to a photodetector 5. The reflected light intensity is separately measured by the photodetector 5 for each scanned point on the object 3. The signals generated by the photodetector 5 are then used to intensity modulate a TV screen 6 which is scanned in synchronism with the scanning spot of light. Known confocal microscope systems such as the one described above have the disadvantage that very bright light sources are required and this usually necessitates the use of lasers. Also, as the microscope images by scanning a spot of light over the object, real-time imaging could not easily be performed.
The optical sectioning and lateral resolution achieved with the confocal microscope described above arises as a result of the illumination and imaging systems being arranged whereby only light which has originated from a specific position in the source plane is detected at the equivalent position in the detector plane. In mathematical terms this is described as the source and detector distributions being delta correlated and with most known confocal microscopes is achieved by employing a single point source and point detector.
In an alternative known confocal system which uses multiple point sources and detectors, an extended light source is used together with a spinning disc containing an array of pinholes usually arranged as interleaving Archimedian spirals. In order to prevent cross-talk between neighbouring pinholes, the pinholes are spaced far apart which results in an extremely low light budget. In general, known confocal systems have the disadvantage that the systems are designed for exact delta correlation between the source and detector distributions which inherently limits the light budget possible with the systems.